Is it me ?

My boyfriend loves to kiss and touch and suck on my breasts, which I am perfectly fine with it actually arouses me as much as if he was touching me anywhere else.

However

I’ve noticed that when he kisses me after his breath tastes like the smell of bo? Or of onions ??? Would it be bc of me sweating ? Is it just bc of my breasts and my diet ? I am very confused bc it is a turn off to taste that.

Am I the only one ? Or has this happened to anyone else ? How would we (or just me or just him) fix this ? I do shower before he gets to my house so I am perplexed as to why it tastes this way.